A cached PasteBin post revealed the threat the FBI was referring
to was targeting CNN, and even included a reference to anchor
Wolf Blitzer.

Here's the post that the FBI was referring to in its bulletin:

By GOP
The result of investigation by CNN is so excellent that you might
have seen what we were doing with your own eyes.
We congratulate you success.
CNN is the BEST in the world.

You will find the gift for CNN at the following address.
https://www.youtube.com/watch?v=hiRacdl02w4
Enjoy!

P.S. You have 24 hours to give us the Wolf.

But hours after the story published, a journalist who writes
about cybersecurity stepped forward and claimed that he wrote the
threat to CNN as a prank, copying another message that he found
online and simply swapping some of the words.

It's important to note that there's no proof that the PasteBin
post mentioning CNN was a prank. Neither Garrett nor the FBI has
posted definitive evidence about the threat.

The FBI issued the following statement to Business Insider when
asked about the Dec. 24 bulletin:

As part of our commitment to public safety, the FBI routinely
shares information with the private sector and law enforcement
community. We take all threats seriously and will continue to
disseminate relevant information observed during the course of
our investigations, in order to help protect the public against
any potential threats.

But if Garrett is to be believed, then the FBI may have been
fooled by a simple prank. If the FBI published a security
bulletin based on anonymous and unauthenticated internet posts,
that's going to make it more difficult for people to believe its
other claims.

Along with the threat against CNN, the FBI also mentioned another
PasteBin post that mocked the bureau's own investigation. If the
prankster is to be believed, that second post could also be fake.